fix(qwen): native-geometry img2img + pipeline-aware strength; record dropped auto/mixed/Z-Image leads

- watermark_remover: _build_qwen_kwargs now passes explicit height/width (via
  _qwen_target_size, floored to /16). Without it QwenImageImg2ImgPipeline defaults to
  1024x1024 and silently squishes non-square inputs, distorting the scene and garbling text.
- watermark_profiles: resolve_strength gains a `pipeline` arg + a Qwen strength ladder
  (_QWEN_VENDOR_STRENGTH, Gemini 0.25), so `--pipeline qwen` gets its certified floor
  automatically; retires the manual "pass --strength 0.25 for Gemini on qwen" workaround.
- fidelity_metrics: replace per-face nearest matching (collided on multi-face images when a
  variant dropped a face, corrupting the identity metric) with a collision-free one-to-one
  assignment (assign_faces_one_to_one). lapvar/LPIPS were always bbox-anchored and immune.
  Regression-guarded by tests/test_fidelity_matching.py.
- docs: record the measured outcomes of the qwen-improvement arc. The Qwen ControlNet
  face-fix is CLOSED (no permissive Qwen detail/tile ControlNet exists; canny carries edges,
  not skin grain). The `--pipeline auto` router + faces+text mixed dual-pass were prototyped
  and DROPPED (controlnet wins faces AND display text: abba CER 0.114 vs qwen 0.379).
  Z-Image-Turbo was tried and dropped (same regeneration limits). qwen stays a manual opt-in;
  controlnet is the default for everything.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/remove_ai_watermarks/cli.py

@@ -762,7 +762,7 @@ def cmd_invisible(
     vendor = vendor_for_strength(source)
     console.print(f"  Input:    {source.name}")
     console.print(f"  Pipeline: {pipeline}")
-    console.print(f"  Strength: {resolve_strength(strength, vendor)}  Steps: {steps}")
+    console.print(f"  Strength: {resolve_strength(strength, vendor, pipeline)}  Steps: {steps}")
 
     t0 = time.monotonic()
     result_path = engine.remove_watermark(
@@ -1075,7 +1075,7 @@ def cmd_all(
             # already lost its C2PA to the visible-removal pass, so reading it would
             # always resolve to the unknown-vendor default.
             vendor = vendor_for_strength(source)
-            console.print(f"    Strength: {resolve_strength(strength, vendor)}  Steps: {steps}")
+            console.print(f"    Strength: {resolve_strength(strength, vendor, pipeline)}  Steps: {steps}")
             inv_engine.remove_watermark(
                 image_path=tmp_path,
                 output_path=tmp_path,